links for 2009-01-27

Initially this document covers, from a high level, various popular VPN technologies and implementations. This document then proceeds to delve into considerable depth about:

* The implementation.
* Lists several vulnerabilities in detail.
* Demonstrates in detail 5 attacks on various versions of the most common of Microsoft's PPTP products, using free, readily available tools
* Explains what each exploit is doing and how it works.
* Brief comparison of MS PPTP to other VPN options available as alternative VPN options, such as other PPTP implementations, L2F, L2TP, IPSEC, IKE, SSH, CIPE, & IPIP.
* Suggested options to decrease the vulnerabilities of using PPTP as a VPN solution.